EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Contribution of vegetation to methane emission produced in the soil of an upland forest: a 13CH4-labelling approach

Caroline Plain1 and Daniel Epron1,2
Caroline Plain and Daniel Epron
  • 1Université de Lorraine, AgroParisTech, INRAE, UMR Silva, F54000 NANCY (
  • 2Kyoto University, Graduate School of Agriculture, Laboratory of Forest Hydrology, 606-8502 Kyoto, Japan (

The role of vegetation on net methane fluxes from upland forest ecosystem has only recently been underlined and is still not fully understand and quantify. Indeed, influences of forest plants on the methane budget could be antagonist, being a net methane producer or emitter in some cases or enhancing the methane consumption in others. But the vegetation in upland forests decreases the net methane uptake by 0 to 63%, and in a few cases, increases the methane uptake up to twice. One of the mains source of methane emission related to the vegetation is the transport of methane from deep anoxic soil layers where the methane is produced to the atmosphere through plant stems.

In order to quantify if vegetation is a preferential way of methane emission in our field site, a 13CH4 labelling had been undertaken in soil (at 40 cm depth) and 13CH4 had been traced in upper soil layers (0, 5, 10, 25 cm depth), on the soil surface with soil chambers with or without herbaceous vegetation and in tree stem chambers for two days after the pulse labelling.

13CH4 was recovered in all compartments even though the forest ecosystem was mainly a methane sink during this period when methane uptake dominated.

In our study, the vegetation (tree stems and herbaceous vegetation) have a limited contribution on the recovery of 13CH4 at the forest scale, which is dominated by soil emissions.

How to cite: Plain, C. and Epron, D.: Contribution of vegetation to methane emission produced in the soil of an upland forest: a 13CH4-labelling approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13502,, 2020


Display file

Comments on the display

AC: Author Comment | CC: Community Comment | Report abuse

displays version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-13502, Martin Maier, 02 May 2020

    Dear Caroline, 


    thank you very much for your nice and interesting display! 

    You could find that labeld CH4 was emitted by the stem surface , which was in the beginning injected into the soil at 40cm depth. Even though the amount is very small, ( smaller than the emission directly via the soil surface) it is still a very intersting finding.

    How exactly did you locate your injection of the labeled CH4? I can imagine, that the architecture of the root network plays a role, and that  the precise injection position, and preferentila aeration along teh injection tubes play a role.

    Very nice study! 

    Kind regards



    • AC1: Reply to CC1, CAROLINE PLAIN, 08 May 2020

      Dear Martin,

      Thank you for your interest and your interesting commentary. The aim of the work was to prove that methane presents into the soil could be emitted by tree stems in upland forest.
      To do that, we have injected the labelled methane at -40 cm depth in 3 porous tubes buried and connected together four years before this labelling experiment. It is the same device we have used in our paper of 2019 or in Parent et al in 2013.
      Yes, we also agree that the root architecture could play an important role of the low amount of 13CH4 retrieve as a large part of the methane injected has been oxidized into the soil. And we have chosen to inject the gas at this depth as it is where production of methane could happen

      I hope this answer to your questions.

      Kind regards,


  • CC2: Comment on EGU2020-13502, Josep Barba, 07 May 2020

    Dear Caroline,

    Many thanks for this interesting study. As Martin said, even if you recovered a small portion of labelled CH4 in the stem emissions, it is a very interesting finding because demonstrates that trees without aerenchima can emit CH4 even without aerenchyma.

    I have a couple of questions:

    1) You mentioned that up to 70% of the injected 13CH4 was oxidised in the upper 25cm, but I was wondering how we can know that? I mean, is this rate based on the amount of 13CH4 recobered, or did you measure 13CO2?

    2) This is more speculative, but do you think there bis a way using isotopes (labelled or stable) to estimate the proportion of stem emitted CH4 coming from soils and heartwood produced?

    Many thanks,


    • AC2: Reply to CC2, CAROLINE PLAIN, 08 May 2020

      Dear Josep,


      Thank you for your interesting comment and questions.

      The aim of this work was for trees, to prove that methane originated from soil could be emitted by tree stems in upland forest.

      Concerning you first question, as we have also traced the labelled methane concentrations into the soil we have modelled the methane consumption in the soil. We would not be able to use the 13CO2 as we have done a 13CO2 labeling (following the 13CH4) as a reference tracer that is supposed to not be consumed into the soil.

      The answer to the second question is more complicated (use of isotope to estimate of proportion of methane emitted by tree stem CH4 coming from soils and from heartwood) but also it is a very interesting question and where we want go.

      So far, I haven't given it much thought. At first sight, I’m not sure it will be possible without labelling. But even with labelling it could be quite hard…. And it requires more time to think about it

      Best regards,



  • CC3: Comment on EGU2020-13502, Nicholas Nickerson, 08 May 2020

    Hi Caroline. Very nice presentation. A quick question about the injection - was it done under pressure (thereby potentially causing advective effects) or was the injected methane allow to diffuse out of the injection tube. Also what was the concentration of injected methane?

    • AC3: Reply to CC3, CAROLINE PLAIN, 14 May 2020

      Dear Nicholas,

      Thank you for your fine commentary and your interest in our study.

      We injected 125 ml of pure 13CH4.  This gas was injected into a 250 ml tube (accurel and all the gas circulation tube).

      We can not guarantee that there is no advection but we tried to minimize it. 

      Best regards,